RadComboBox Scrolling Selection Locks Browser

I have a very specific problem with the RadComboBox. I am using it in a RadWindow that is opening like a dialog, and it is near the bottom of the window, so that the expanded drop down has to open up. If I have enough items that the vertical scroll bar is used, I can select an item and move on, but if I go back to the ComboBox to change my selection, it locks and freezes the whole browser window.

I am using Q1 controls, IE Version 7.0.6001.18000.

This lockup/freeze does NOT occur in Firefox 3, and operates as expected.

I checked the vertical versus horizontal scroll, wrap versus no wrapping text, and it seems related to the vertical scroll. If I limit the items in the list so that it does not scroll, it does not lockup. I tried the default and the Vista skin with the same results.

Setting EnableVirtualScrolling did not fix the issue, but when I put in a manual height, it does fix the issue. I tested add/removing the manual height, and it did fix/break the issue with just saving the ASPX and refreshing the page (no recompile).

I have an earlier version of IE 7 that I am going to test with for the auto height. I am not happy with having to manually set the height appropraitely, but it is a workaround that seems to work.

Same problem with a different machine on IE 7 Version 7.0.5730.13. The statement declaring the combo box is simple, and it is not linked to data source (the items are loaded manually). It is not using Ajax nor part of an Ajax update. I'll see if I have time to create a new project to isolate this example.

Rosi

We will be happy to help you resolved this issue, but we need more information on the matter. Could you please send us a live url or open a support ticket and send us a sample running project to test it locally?

Andrew Marmara

I would like to know the outcome on as I also have this problem. It is very sensative to the size of the combo list and the page its on. There is obviously an infinite loop involved here (looks like it is in your javascript), as the cpu usage for the IE browser process is high. Other applications and browser windows operate as normal (although are less responsive due to the cpu hogging infinite loop).

Rosi

This problem is very strange and we are still not able to reproduce it at our side.

I suggest you prepare a small running project illustrating the problem an send it to us via support ticket. We will test it locally and provide you with a solution.

Also I suggest you check if the e.EndOfItems property of the event argument of ItemsRequested event is set to true when the end of the items is reached. You can see how this is done in our online example.

Regards,

Rosi
the Telerik team

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Donna Padilla

I had a very similar issue. I have a rad combobox on a radwindow sized at 600px x 800px. The combobox had 31 items in it. When I clicked on the combobox, IE would freeze up and never recover. A vertical scrollbar would appear on the RadWindow before the freeze occured. More info and troubleshooting results:

The radcombo is placed within a table that is within a fieldset near the bottom of the radwindow.

If I tabbed to the radcombo and hit the down arrow (instead of clicking on radcombo), I was able to cycle through the radcombo items with no problem.

If I moved the radcombo to the top of the radwindow, it worked fine.

If I moved the radcombo to another location within a fieldset within a table near the top of the radwindow, it worked fine.

If I moved the radcombo to the very bottom of the radwindow but outside of containing controls (right above the </form> tag), it worked fine.

If I put the radcombo in its original location, but only add 5 items instead of 31, it worked fine.

So the problem seems to occur when:
- radcombo is used on radwindow
- radcombo has enough items in it so that expanding the drop down would force the radwindow to scroll
- radcombo is placed in a vertical position on the screen so that expanding the drop down would force the radwindow to scroll
-the radcombo is placed within other containing controls (not sure if it is the table or fieldset or combination of)

Setting the Height on the radcombo to a height that would prevent RadWindow scrolling fixes the issue, as mentioned previously.

I was also able to work around this issue by explicitly setting MaxHeight to some value. This is better than setting explicitly Height which can look ugly when the values do not fill the height of the dropdown. I'm guessing it keeps the javascript from remaining in an infinite loop trying to dynamically calculate the height when limited by some containing control.

Ivan Danchev

As I mentioned in this thread we would need to reproduce the issue in order to confirm whether it is a bug in the control or the observed behavior is caused by custom code. Demonstrating the problem in the support ticket on the same subject would be helpful in determining the cause for the issue.

Regards,
Ivan Danchev
Telerik

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